The use of shocks to kill cancer cells and to disrupt tissue for use in medical research is known. Two articles reporting the use of chemical explosions, such as gunpowder, are "An Explosion Instrument for Disrupting Tissues and Cells", J. A. Reyniers and M. R. Sacksteder, Journal of the National Cancer Institute, Vol. 25, No. 3, September, 1960; "Killing of Ehrlich Cancer Cells by Explosive Shocks", L. R. Maxwell et al., Oncology 24:187-192 (1970). The devices described in these articles, however, are limited in use. The devices do not have a wide range of applied pressures, control of the pressure is difficult, and recovery of the sample, particularly an uncontaminated sample, is not always easy. The instrument, and method, of this invention is superior to these devices in that it provides for a wide range of pressures which can be applied to the sample in a controlled fashion. The device also allows for easy removal of the sample while keeping differently treated portions of the sample separate. Unlike the device of Reyniers et al., the instrument of this invention permits the application of a broad range of pressures to the sample in a controlled fashion. The magnitude of the pressures and the length of time they are applied to the sample is controlled by the acceleration of the piston, the size of the sample, the nozzle, the length of the extension, etc., as more fully described below. In the device of Reyniers et al., there is no acceleration of a piston to impact the sample and create a hypervelocity jet. Accordingly, the high pressures and forces applied to the sample cannot be attained and the pressure cannot be controlled over the wide range of pressures as in the instrument of this invention.